Conventionally, a vehicle is mounted with a warning device for generating a warning for another vehicle, a pedestrian, or the like around the vehicle. A volume level of the warning is set of such a level as to satisfy the legal standard in order to make the warning recognized by a driver in another vehicle. As a result, pedestrians may feel that the volume level is excessively high in some cases.
In view of such a problem, there is a vehicle audible alarm device of an automobile or the like as disclosed in Japanese Utility Model Registration No. 3094635, for example, in which a volume level can be adjusted to produce a sound in an arbitrary volume level range in an audible range according to a place and time. This vehicle audible alarm is formed of a main audible alarm for producing a sound at a volume level set in a range of legal standard values and an audible alarm for pedestrians and a quiet audible alarm for producing sounds at volume levels lower than the main audible alarm and in an audible range. The vehicle audible alarm device can whistle and produce a sound while arbitrarily switching among the main audible alarm, the audible alarm for pedestrians, and the quiet audible alarm.
With the vehicle audible alarm device disclosed in the above-described gazette, the audible alarm for pedestrians can whistle and produce the sound to thereby call attention of pedestrians or passersby on bicycles and the like to approach of a vehicle such as an automobile to prevent danger. Moreover, especially in midnight residential areas and near medical facilities, educational facilities, and the like such as hospitals and schools where quiet is desired, the quiet audible alarm can whistle and produce the sound to thereby call attention of pedestrians or passersby on bicycles and the like in these areas to approach of a vehicle such as an automobile to prevent danger except when an audible alarm at a high volume level is absolutely necessary due to sudden danger or to prevent an accident.
In recent years, as one of measures for environmental issues, a hybrid car, a fuel-cell vehicle, an electric car, and the like which travel by a driving force from a motor are receiving attention. Because an operating sound of the motor is quieter than an engine operating sound in such a vehicle when it travels by the motor, it becomes necessary to make presence of the own vehicle recognized by another vehicle or pedestrians around the vehicle.
In view of such a problem, there is a hybrid vehicle for preventing pedestrians and the like from becoming less likely to notice approach of the vehicle when the vehicle travels only by a driving force of an electric motor as disclosed in Japanese Patent Laying-Open No. 2004-153929. The hybrid vehicle includes an engine and the electric motor for generating the driving force for the vehicle, a driving force source switching means for controlling a switch between generating sources of the driving force, and a vehicle approach informing means for generating a sound for informing an outside of the vehicle of approach of the vehicle when the driving force source switching means switches the generating source of the driving force to the electric motor.
With the hybrid vehicle disclosed in the above-described gazette, it is possible to prevent the pedestrians, passengers of light vehicles, and the like, for example, from becoming less likely to notice approach of the hybrid vehicle when the hybrid vehicle travels by obtaining the driving force from the electric motor.
There is also a pedestrian danger sensing system for an electric car or the like and for preventing an accident of a pedestrian caused by reduction of traveling noise due to introduction of the electric car by an inexpensive device as disclosed in Japanese Patent Laying-Open No. 2002-2424. The pedestrian danger sensing system is provided with an external volume level automatic measuring and sensing device controlled by a computer. The pedestrian danger sensing system generates automatically-variable mimic traveling noise according to a traveling environment from a speaker. The pedestrian danger sensing system senses an object by using a laser beam in a mountain-ringed region or in a low traffic area. The pedestrian danger sensing system automatically makes a switch to an object sensor by using a radio wave at the center of downtown or in a high traffic area. The pedestrian sensing system generates an emergency danger sound for a pedestrian or the like from the speaker to avoid a sudden accident and warns the pedestrian or the like by a sound transmitted from the vehicle to a cellular phone or the like to avoid a sudden accident.
The pedestrian danger sensing system disclosed in the above-described gazette is advantageous in that it is disposition of a device for contributing to prevention of a new type of traffic accident caused by introduction of the electric car, that the system can be formed readily by using existing devices, and that the system itself can readily utilize new technologies when a car navigation system and the new technologies are introduced.
Moreover, there is also a pedestrian danger sensing system for an electric car or the like and for preventing an accident of a pedestrian caused by reduction of traveling noise due to introduction of the electric car by an inexpensive device as disclosed in Japanese Patent Laying-Open No. 2002-2424. The pedestrian danger sensing system is provided with an external volume level automatic measuring and sensing device controlled by a computer. The pedestrian danger sensing system generates automatically-variable mimic traveling noise according to a traveling environment from a speaker. The pedestrian danger sensing system senses an object by using a laser beam in a mountain-ringed region or in a low traffic area. The pedestrian danger sensing system automatically makes a switch to an object sensor by using a radio wave at the center of downtown or in a high traffic area. The pedestrian sensing system generates an emergency danger sound for a pedestrian or the like from the speaker to avoid a sudden accident and warns the pedestrian or the like by a sound transmitted from the vehicle to a cellular phone or the like to avoid a sudden accident.
The pedestrian danger sensing system disclosed in the above-described gazette is advantageous in that it is disposition of a device for contributing to prevention of a new type of traffic accident caused by introduction of the electric car, that the system can be formed readily by using existing devices, and that the system itself can readily utilize new technologies when a car navigation system and the new technologies are introduced.
Because such a situation is not taken into consideration in Japanese Patent Laying-Open No. 2002-2424, there is a possibility that a person unexpectedly approaches the vehicle as described above.
Furthermore, in Japanese Patent Laying-Open No. 1083187, in a hybrid vehicle traveling in a plurality of operation modes, a dummy sound similar to an engine sound in traveling by using an engine as a power source is generated in a motor traveling mode in which the vehicle travels by using only an electric motor as the power source. Thus, it is possible to make existence of the own vehicle recognized by people around the vehicle and to prevent a sense of discomfort in passengers aroused by a change in the sound of the power source due to the operation mode.
There is also a technique for reducing a volume level of a dummy engine sound or silencing the sound so as to carefully listen to sounds in surroundings when an electric car is positioned in an area where the car is guided by a navigation system, a guidance area, an urban area, a vicinity of a railroad crossing, and the like as disclosed in Japanese Patent Laying-Open No. 2002-233001.
When a hybrid vehicle mounted with an engine and a driving electric motor travels by a driving force of the driving electric motor, an operating sound of the driving source is quieter than that in case of traveling by a driving force of the engine in some cases. Therefore, when the hybrid vehicle travels by the driving force of the driving electric motor, people around the vehicle may not notice existence of the vehicle. As a result, occasions of giving warnings become frequent. If the warnings at a volume level high enough to satisfy the legal standard are generated frequently, such warnings make people around the vehicle unpleasant. Because the vehicle audible alarm device disclosed in Japanese Utility Model Registration No. 3094635 is made without making provision for the hybrid vehicle, the above-described problem is not taken into consideration.
Moreover, in the hybrid vehicle, if the warning is generated when noise generated from the vehicle during operation of an internal combustion engine is loud, the people around the vehicle recognizes existence of the vehicle based on the noise generated from the vehicle and therefore generation of the warning may become unnecessary. Moreover, if the vehicle travels in an urban area, for example, there are many people around the vehicle. Therefore, if unnecessary warnings are generated frequently in such an area, the warnings make the people around the vehicle unpleasant.
In the hybrid vehicle disclosed in Japanese Patent Laying-Open No. 2004-153929, the switch is made to the driving force of the electric motor when the vehicle comes into a predetermined location to generate the warning and therefore the above-described generation of unnecessary warnings is not taken into consideration.
Moreover, if the warning is set to be generated when the object is detected, there is a possibility that the warnings are generated frequently. For example, in the urban area, there are many people around the vehicle and therefore the frequently generated warnings may make the people around the vehicle unpleasant. Especially, in case of the hybrid vehicle, the noise generated from the vehicle is loud during operation of the internal combustion engine and therefore it is possible to make the existence of the vehicle recognized by the people around the vehicle without generating the warning, which causes a problem of generation of unnecessary warnings.
Because the pedestrian danger sensing system disclosed in Japanese Patent Laying-Open No. 2002-2424 is made without making provision for the hybrid vehicle, the unnecessary warnings are generated as described above.
Furthermore, when the sound of the driving source is quiet, it is necessary to make the existence or a start of the vehicle recognized by the people around the vehicle earlier in order to allow the vehicle to start more safely. If the people around the vehicle recognize the existence or start of the vehicle late when the vehicle starts, there is a possibility that the people unexpectedly approach the vehicle.
Moreover, if the vehicles generating sounds other than traveling noise travel in a group, the sounds generated from the respective vehicles overlap each other and may make surrounding people unpleasant. For example, in a quiet residential area and the like, such a situation may worsen a residential environment.
Especially when music and melodies are generated from the vehicle, the people around the vehicles are expected to feel the vehicles extremely noisy. Therefore, it is preferable that a vehicle such as a hybrid car having a mechanism of generating a sound for making existence of the vehicle recognized by surrounding people is provided with a mechanism for controlling the generated sound according to the surrounding situation.